Liquid fuel



Patented Oct. 19, 1937 UNITED STATES LIQUID FUEL Vanderveer Voorhces,Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., acorporation of Indiana No Drawing.

3 Claims.

This invention relates to an improvement in fuels for internalcombustion engines and more particularly fuels for engines of the directinjection type wherein the fuel is forced, under high 5 pressure,directly into the combustion zone. Examples of such engines are thewell-known Diesel and semi-Diesel engines employing either the highpressure fuel system or the injection pump system.

In the operation of these engines, especially with the lighter grades ofdistillate fuel oils such as are commonly used for engines of the highspeed type, a great deal of difiiculty has been encountered with erosionof fuel valves and fuel 15 pumps. This difliculty has been traced to thelow viscosity of the fuel, especially at the somewhat elevatedtemperatures at which it is used, under which conditions the rubbingmetal surfaces of pump plungers and valves rapidly be- 20 come worn.Even a slight amount of wear of these parts of the engine leads toserious consequences because of the very small clearances betweenoperating parts required in handling and imecting the minute quantitiesof fuel necessary 25 for the operation of these engines. Thus, in amuiti-cylinder high speed, automotive Diesel engine the amount of fuelinjected per stroke is only a small fraction of a cubic centimeter andconsequently a verylittle wear in the fuel valve or pump results inerratic operation of the engine by varying the volume of the fuelinjected per stroke.

Attempts to overcome this difiiculty have heretofore been made byincreasing the viscosity of the fuel employed. However, any benefitobtained by so doing is more than offset by improper distribution andunsatisfactory combustion of the more viscous fuel as a result of itscorrespondingly decreased volatility. I have now discovered a means bywhich the viscosity of the fuel may be significantly increased while atthe same time maintaining substantially the same volatility andcombustion characteristics. 'In fact, I am even able to increase thevolatility beyond that previously employed and simultaneously increasethe viscosity, with resulting improvement in lubrication of fuel pumpsand valves as hereinafter described.

My new Diesel fuel oil comprises a distillate fuel of the desiredvolatility and combustion characteristics, together with a small amountof a special viscosity producing agent which is a resinous productproduced by the polymerization of olefin hydrocarbons. The resinousproduct which I employ is a non-crystalline plastic hydrocarbonmaterial, soluble in hydrocarbon oils and. plastic at all ordinarytemperatures, from well below F. to temperatures above 300 F. and evenas high as 400 F. where the material still retains its body or viscosityto a large degree.

Application October 31, 1935, Serial No. 47,609

It is characterized by light color, high stability and high molecularweight, usually between 1,000 and 12,000. The empirical formula of theresin is substantially CnHin and on heating to decom positiontemperature it depolymerizes without the formation of undesirable cokeand other residues.

The plastic resin may be most conveniently made by polymerization ofliquid isobutylene at low temperatures, below 0 F. and preferably -40 tol00 F. In carrying out the polymerization, a suitable catalyst isnecessary and boron fluoride or aluminum chloride may be used for thispurpose, the amount required being from about 0.1 to If boron fluoride,which is a gas, is used it may be conveniently bubbled into the coldisobutylene while the latter is rapidly agitated. The reaction requiresfrom several minutes to a half hour, the isobutylene being converted toa plastic mass at the end of that time. For convenience in handling andagitating it is usually desired to employ a diluent, which mayconveniently be hexane, butane, propane, or in the case of very lowtemperature operations, liquid ethane. The

.diluent may be readily removed from the product by evaporation,preferably after the product has been neutralized and washed to removethe catalyst. If desired, the isobutylene may be polymerized directly inthe presence of the distillate fuel oil in which it is desired to beused.

Other oleflns besides isobutylene may be employed as starting materialsfor making the plastic resin; for example, normal butylene, amylene,hexylene and mixed olefinic hydrocarbons and saturated hydrocarbonscondensed from cracking still gases, preferably those boiling in therange of 20 to 50 F.

The amount of plastic resin required to make the product of thisinvention may be from 1 to of the weight of the oil treated and amountsof about 2 to 5% are usually preferred. A suitable fuel oil employed forthe purpose possessed the following distillation characteristics asdetermined by A. S. T. M. distillation:

This oil was blended with 2% and 5% of a plasticresin from isobutylenepolymerization and tested with 9. Diesel engine of the high speed type.The

non-volatile plastic resin did not interfere in any way with thecombustion of the fuel in the engine, and improved lubrication of thefuel valve was obtained. The viscosity of the fuel was increased from 39seconds Saybolt at 100 F. to 42.2 seconds Saybolt at 100 F. by theaddition of 2% of the resin and to 48.3 seconds Saybolt at 100 F. by theaddition of 5% of the resin. The cetene number of the fuel which was 64before the addition of the resin, remained unchanged.

The amount of resin added will vary with the initial viscosity andvolatility of the fuel. Thus a light, low boiling fuel will require moreresin to raise the viscosity to the desired extent. It is preferred toincrease the viscosity above seconds Saybolt, and a range of 45 toseconds Saybolt is desirable. employed however.

As previously mentioned. the use of the plastic resin in Diesel fuels isespecially applicable to the Higher viscosities may be lighter fuelssuch as petroleum distillate fuel having the following characteristics:

Flash point -F Pour point do 35 Distillation A. S. T. M. 10% point F 395point do 450 Maximum .do 490 Viscosity-Saybolt at F sec 32 The termplastic hydrocarbon resin asused 'point below about 650 F., said oilstending to cause such excessive wear on the fuel pump and ..valves as torender them inoperative in worn condition for such fuels, comprisingadding to the said light Diesel fuel oil suflicient isobutylene polymer,between 1 and 10%, to raise the viscosity to a pump and valve sealingand lubricating consistency without substantially adversely affectingthe combustion characteristics of the said light Diesel fuel oil, andthen injecting the fuel into said engine through said pump.

2. The method of claim 1 wherein the viscosity of the said light Dieselfuel oil before the addition of isobutylene polymer is about 32 to 39seconds Saybolt at 100 F.

3. The method of claim 1 wherein the said isobutylene polymer is aplastic hydrocarbon resulting from the polymerization of isobutylene atlow temperatures below 0 F. in the presence of a metal halide catalyst.

VANDERVEER VOORHEES.

I v CERTIFICATE OF CORRECTION. v t Patent No, 2,096,218. October 19,1957.

VANDERVEER VOORHEES It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 2, first column, line 21 in the table, for "55" read55; and that thesaid llet ters Patent should be read with thiscorrection therein that the same may conform to; the record of the case.in the Patent Office.

Signed and sealed this 16th day of November, A. D. 1957.

Henry Van Arsdale,

(Seal). Acting Commissioner of Patents.

